As described in patent application No. FR0756066, turbine engine retention disks, such as disks 1 (Cf. FIG. 1) of a first stage 2 and of a second stage 3 of a low pressure turbine, conventionally comprise at their periphery a plurality of substantially transversal slots 4 in which the roots 5 of the blades 6 are assembled by insertion.
In addition, a platform is arranged between two adjacent blades 6 (not represented). The platform assembly that the retention disk comprises enables the profile of a stream to be formed, above which, when the turbine engine is operated, the gas circulates, the temperature of which is about 700 degrees.
It follows that the roots 5 of the blade 6 and the slots 4 are directly exposed to these high temperatures. Therefore, it is important to cool them to prevent any damage to the retention disks 1.
For this purpose, tapping off part of the air that flows outside of the flow stream of the low pressure turbine (i.e., from the compression chamber) to transport it via a cooling circuit to the slots 4 of the retention disks 1 is known.
The retention disks 1 of the first stage 2 and of the second stage 3 are centered on a longitudinal axis X of the turbine engine and are fixed to each other by means of bolted connections 7 regularly distributed around this axis X.
Each retention disk 1 comprises an annular bridle 8 presenting an upstream face on which is assembled an annular flange 9 forming an annular cavity 10. The latter is open at its lower end at the level of the compression chamber where air circulates, the temperature of which is about 400 degrees. At its opposite end, this annular cavity 10 opens in the bottom of each of the slots 4 and thus enables the slots 4 and the blade 6 roots 5 to be cooled. Cooling of the bottom of the slots 4 protects the retention disk 1 from any damage due to a high temperature.
On the other hand, the manufacture of retention disks 1 in conformance with the aforementioned disks is costly. This cost is particularly due to the need to manufacture, one at a time, by means of a stapler type machine tool, the slots 4 of the retention disk 1, which retention disk 1 usually comprises 160 slots 4.
In addition, the annular bridles 8, annular flanges 9 and the bolting elements 7 of a low pressure turbine constitute a considerable part of the mass and manufacturing cost of the low pressure turbine.